Clamps are devices used to secure articles to a supporting surface. One type of clamp is a tube clamp, that is used to engage and secure a tubular article to a supporting surface. The tubular article may be a pipe, hose, duct, line, cable or harness. The supporting surface may be an engine block or chassis member for a vehicular application, or a wall or beam for a architectural application.
In vehicle applications clamps are used to secure hydraulic, pneumatic, mechanical and electrical tubes. Hydraulic tubes or lines are commonly used for a variety of systems including: brake systems, fuel systems, heating, ventilation and air conditioning (HVAC) systems and power steering systems. Common systems using pneumatic tubes or hoses include: lift, leveling and stabilizing systems. Mechanical tubes or cables are commonly used on a variety of systems including: hood and trunk release cables, parking brake cables and shifter cables. Electrical tubes or harnesses connect the various electrical systems and components on the vehicle including: power generation and storage, controllers and sensors. A variety of clamps are currently used to secure these tubes on a vehicle.
Metal clamps are often used for rigid attachment of heavy tubes in demanding environments, whereas plastic straps are often used for flexible attachments. A metal clamp may damage a tube if it is not properly assembled and does not properly engage the tube. If there is any clearance between the clamp and the tube when retained, then noise or wear of the tube may develop over time. Plastic straps are elastic and conform to the exterior shape of a tube, which may prevent wear. However, plastic straps typically do not have the strength to support larger tubes and the plastic straps are not suited for high temperature applications.
Grommeted clamps have been developed for applications requiring the high strength of a metal clamp and elasticity of a plastic strap. These clamps typically include an elastic material that conforms to the exterior of a tube with a metal bracket to clamp around the elastic material and anchor the tube to a supporting surface.
One common approach for a grommeted clamp includes shipping the metal portions along with an elastic grommet as individual components, where one assembles the grommeted clamp assembly prior to securing the tube. This approach can be time intensive, and can lead to potential problems if the grommeted clamp is not assembled properly.
Another approach for a grommeted clamp assembly includes over molding an elastic material to a metal clamp subassembly, then providing a single grommeted clamp assembly to the user. This approach saves assembly time at the plant, however many products that are currently available do not properly secure the tube.
One example of an over molded grommeted clamp assembly that does not properly secure the tube includes a metal clamp that is over molded with elastic material while it is in an open position. Once the grommeted clamp assembly is closed around a tube, the cavity formed by the elastic material is of an irregular shape and does not conform to the exterior portion of the tube. The clearance between the grommeted clamp assembly and the tube may result in wear to the tube and objectionable noise.
Another example of an over molded grommeted clamp assembly that does not properly secure the tube includes a metal clamp that is over molded with elastic material while it is in a closed position. The elastic material resists plastic deformation, and results in a grommeted clamp that is difficult for a user to open and engage the tube during assembly.